In dungeons, w/e will just save you a bunch of seconds by shaving off a couple %, so not a big deal. Fire away.

In alpha normals, other than LBing early during checker since you get most of it back from the meteor circles I wouldn't be surprised if people saved LB. Each turn has a bunch of accident spots where you can just wipe and waste minutes redoing it. Better to save for a healer lb3/tank lb3 than shaving off a couple % IMO and just fire it at the end if its unused and the boss is about to die.

O9N - double stacking the stacks - I don't know why but this happens a lot usually right at the end during an earth phase, causing a wipe after 6-8 minutes. Healer lb can fix this if one of the healers get out otherwise you wipe and have to do it again from the beginning. This one doesn't matter too much.

O10N - the 2nd akh morn after earth shakers + horrid roar - even ok parties sometimes wipe here because they forget about the stack while dodging the circles in different directions or a bunch of people died to the earth shakers before - i've tank lb3'd through this twice now since the party kept dying at this spot.

O11N - star/lar accidents, especially the one after the electric slide stack that starts his star/lar combo facing the party and people get mixed up since it is opposite due to facing.

O12N - phase 3 tank proximity meteors, if I see the party at half HP and people not moving i'll tank lb3 if both the healers are going to die from the damage. Only had to do this once so far.